Experimental Analysis and FEM Simulation of Antigravity Loop-Shaped Heat Pipe for Radio Remote Unit

This paper presents the thermal performance analysis of the antigravity loop-shaped heat pipe (AGLSHP) used for radio remote unit. The experiments are conducted by mounting the system vertically over a heat source set above the condenser with forced convection. The transit temperature distributions of the AGLSHP with two different antigravity lengths are measured and evaluated via increasing the input power from 10 to 100 W. Thermal resistance and effective thermal conductivity under steady state are both studied in this paper. The experimental observations are validated via ANSYS simulation. The results show that the maximum operating evaporator temperature of AGLSHP-400 is 12.5 °C higher than that of AGLSHP-300 when the heating load is 100 W. As the heat input increases, the total thermal resistance decreases first and then goes up, while the thermal conductivity shows the opposite tendency. The lowest values of the thermal resistance obtained are 0.20 °C/W for 400-mm antigravity length and 0.14 °C/W for 300-mm length. The heating load and the effective thermal conductivity of the heat pipe are critical to the accuracy of the simulation results. The simulation results are found in agreement with the experiment. The averaged discrepancy between the experimentally measured average temperature and the finite element method predicted average temperature at the evaporator is less than 4%.